We developed a novel concept of a highly efficient, transparent, and flexible triboelectric nanogenerator (TF-TENG) based on a metallic nanowire-embedded conducting polymer as a contact electrode. In contrast to metals that are highly tribopositive but opaque and less flexible, a conducting polymer, poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS), is transparent, flexible, and shows moderately high tribonegativity which is capable of accepting the electrons from the counter surface in the TF-TENG during contact. The silver nanowire layer placed beneath the conducting polymer layer results in the increase of the conductivity and the surface roughness as well. The output voltage was about 160 V. The output current (> 50 µA) was at least five times larger than any of existing TF-TENGs and a substantially high value of the instantaneous power density (> 1.5 mW/cm2) was obtained. Using such TF-TENG, a self-powered system for instantaneous touch visualization was demonstrated using a liquid crystal device. Our TF-TENG, built on a stretchable substrate, exhibits high transparency and excellent output performance on an arbitrary surface like a human skin or a fabric so that it enables to devise a variety of power sources for flexible and transparent electronics.